Fluid coking to produce a carbon black feed stock



May 17, 1960 J. F MOSER, JR

l FRACTIONATORL.

2 PITCH FEED- FLUID COKER GAS 9 2% NAPHTHA l0 HEATING OIL HEAVY GAS OILBOTTOMS CARBON BLACK FEED STOCK STEAM Inventor By I Attorney John FMoser, Jr.

United States Patent FLUID COKING TO PRODUCE A CARBON BLACK FEED STOCKApplication June 25, 1951, Serial N0. 667,834 4 Claims. or. 208-100) Thepresent invention relates to an improved process for preparing a carbonblack feed stock. More particularly, it relates to a process of thisnature integrated into the fluid coking operation.

There has recently been developed an improved process known as the fluidcoking process for the production of fluid coke and the thermalconversion of heavy hydrocarbon oils to lighter fractions, e.g., seeU.S..Patents 2,735,349 and 2,735,806.

The fluid coking process unit consists basically of a reaction vessel orcoker and a heater'or burner vessel. In a typical operation the-heavyoil to be processed is injected into the reaction vessel containing adense, turbulent, fluidized bed of hot inert solid particles. A stagedreactor can be employed. Uniform temperature exists in the coking bed.Uniform mixing in the bed results in virtually isothermal conditions andeffects instantaneous distribution of the feed stock. In the reactionzone the feed stock is partially vaporized and par-- tially cracked.Eflluent vapors are removed from the coking vessel and sent to afractionator for the recovery of gas and light distillates therefrom.Any heavy bottoms is usually returned to the coking vessel. The cokeproduced in the process remains in the bed coated on the solidparticles. Stripping steam is injected into the stripper to remove oilfrom the coke particles prior to the passage of the coke to the burner.

The heat for carrying out the endothermic coking reaction is generatedin the burner or heater vessel, usually separate. A stream of coke isthus transferred from the reactor to the burner vessel, such as a fluidbed or transfer line burner, employing a standpipe and riser system; airbeing supplied to the riser for conveying the solids to the burner.Sufiicient coke or added carbonaceous matter is burned in the burningvessel to bring the solids therein up to a temperature suflicient tomaintain the system in heat balance. The burner solids are maintained ata higher temperature than the solids in the reactor. Coke, equivalent toabout 5% to 10% based on feed, is burned for this purpose. This mayamount to approximately 15% to 30% of the coke made in the process. Thenet coke production, which represents the coke make less the cokeburned, is withdrawn.

Heavy hydrocarbon oil feeds suitable for the coking process includeheavy crudes, atmospheric and vacuum bottoms from crude, pitch, asphalt,other heavy hydrocarbon petroleum residua or mixtures thereof. Typicallysuch feeds can have an initial boiling point of about 700 F. or higher,an A.P.l. gravity of about 0 to 20, and a Conradson carbon residuecontent of about 2 to 40 wt. percent. (As to Conradson carbon residuesee A.S.T.M. Test D189 4l.)

It is preferred to operate with solids having a particle size rangingbetween 100 and 1000 microns in diameter with a preferred particle sizerange between 150 and 400 microns. Preferably not more than 5% has aparticle size below about 75 microns,-since small particles tend toagglomerate or are swept out of the system with the 2 gases. While cokeis the preferred particulate solid, other inert particulate solids suchas spent catalyst,-pumice, sand, kieselguhr, Carborundum, and aluminacan be employed.

The economic attractiveness of the fluid coking process is affected bythe production of other valuable products besides the conventionaldistillate components, e.g., fluid coke for the manufacture of carbonelectrodes. It is consequently desirable to be able to increase thenumber of these products.

This invention provides a process for preparing a carbon =black feedstock by the fluid coking operation. The process comprises continuouslyfractionating the coker product vapors to separate a heavy gas oilfraction boiling in the range of about 700 to 1000" F. and a heavierfraction boiling above about 1000 F. The heavier, 1000 FJ+ fraction iswithdrawn after a once-through operation rather than being recycled asin conventional coking. The heavy gas oil .is, however, continuouslyrecycled and a portion of the approximately 700 to 1000 F.resulting gasoil from the recycling operation is blendedwith the withdrawn heavierfraction to produce the carbon black feed stock. About 2 parts by volumeof recracked gas oil is thus blended withabout 3 parts by volume of theheavier fraction. This unique blend of recracke d gas oil andonce-through bottoms constitutes a satisfactory carbon black feed stockwhereas each stream aloneis not satisfactory. The 'fluid coker isoperated at somewhathigher than conventional temperatures as detailedsubsequently in the .tabular presentation. V I

This invention will be better understood by reference to an example andthe flow diagram shown in the drawing.

In the drawing the numeral 1 is a coking vessel constructed of suitablematerials for operation at 1025' F. A :bed of coke particles preheatedto a sufficient temperature, e.g., 1200 F., to establish the requiredbed temperature of 1025 F. is made up of suitable particles of to 400microns. The bed of solid particles reaches an upper level indicated bythe numeral 5. The bed is fluidized by means of a gas such as strippingsteam entering the vessel at the stripping portion near the bottomthereof via pipe 3. The fluidizing gas plus vapors from the cokingreaction pass upwardly through the vessel at a velocity of l ft./sec.establishing the solids at the indicated level. The fluidizing gasserves also to strip the vapors and gases from the coke which flows downthrough the vessel to the heater. A stream of solid particles is removedfrom the coking vessel via line 8 and transferred to the heater, notshown.

A pitch to be converted is introduced into the bed of hot coke particlesvia line 2, but preferably at a plurality of points in the system. Thepitch upon contacting the hot particles undergoes decomposition and thevapors resulting therefrom assist in the fluidization of the solids inthe bed and add to its general mobility and turbulent state. The productvapors leave through cyclone 4 and line 6.

The product vapors are then fractionated in fractionator 7. A dry gasfraction is withdrawn through 16, a naphtha fraction through line 9, aheating oil fraction through line 10, and the heavier 1000 Fu-I-fraction through 11. The 700-1000 F. gas oil fraction is continuouslyrecycled through lines 12 and 13 to the coker 1. A portion of theresulting 700-1000 F. gas oil produced from the recycling operation iswithdrawn through lines 12 and "14 and blended with the heavier fractionin line 15 to give the carbon black feed stock. About two parts of gasoil are blended with three parts of the heavier fraction.

The actual preparation of carbon black is no part of this invention andthe processing of the feed stock thus follows conventional procedures,e.g., see US. Patents 1,535,214, 1,890,188, 1,986,198 and 2,666,734.

The advantages of this process will be apparent to the skilled in "theart. The flexibility of the'fluid coking process is "improved and avaluable feed stock is provided. The conditions in the fluid coker forfuels are also listed below for completeness.

Conditions in fluidpoker reactor Broad I Preferred Range RangeTemperature, 900-1, 200' 1, 000-1, 050 Pressure, Atmospheres 1-10 1. 5-2S ugerfieial Velocity-of Fluldizing Gas,:it./sec-. t 0.2- 0.5-4 00 eCirculation (Solids/oil Ratio) 2 30 7-15 Conditions inheater BroadPreferred Range Range Temperature, F. L 1, 100-L600 1,1751,325 Superfilal Velocity of Fluldizlng GasflL/sec; 1-5 2-4 It is'tobe understoodthat this-invention'is not limited to the specific examples which have:been offered merely asillustrations and that modifications may be madewithout departing fromthe spirit of the invention.

What is claimed is:

1. In a process for coking a heavy hydrocarbon oil coking charge stockby contacting the charge stock at a coking'temperature with a dense,turbulent, fluidized bed of inert particulate solids in a coking zone,the oil being converted to product vapors and carbonaceous solids beingcontinuously deposited on the inert solids in the coking zone;removing-product vapors'fromthe coking zone; circulating the inertsolids through an-external heating zone to raise their temperature andrecycling the heated solids to the coking zone to supply heat thereto,the improved method of preparing a carbon black feed stock whichcomprises the steps of continuously tractionating the product vapors toseparate a heavy gas oil fraction boiling in the range of about 700 :to1000 F. and a heavier fraction boiling above about 1000" F.,;withdrawing the heavier fraction; continuously recycling a portion ofthe 700 F. to 1000 F. heavy gas oilfraction to said coking zone forfurther cracking; withdrawing the resttof the 700 to 1000 F. heavy gasoil thus produced from the recycling operation and blending it with thewithdrawn heavier fraction to produce the carbon black feed stock.

2. The process of claim 1 in which the coking temperature utilized is inthe range of 1000" to 1050 vF. 3. The process of claim 2 in which abouttwo parts by volume of the heavy gas oil are blended with about threeparts by volume of the'heavierffraction.

4. A process according to claim ,1 .wherein the fractionation of theproduct vapors is carried out to separate a heating oil fraction'boiling'between the naphtha fraction and'the heavy gas oil fraction.

' References Cited in the file of this patent UNITED STATES PATENTS

1. IN A PROCESS FOR COKING A HEAVY HYDROCARBON OIL COKING CHARGE STOCKBY CONTACTING THE CHARGE STOCK AT A COKING TEMPERATURE WITH A DENSE,TURBULENT, FLUIDIZED BED OF INERT PARTICULATE SOLIDS IN A COKING ZONE,THE OIL BEING CONVERTED TO PRODUCT VAPORS AND CARBONACEOUS SOLIDS BEINGCONTINUOUSLY DEPOSITED ON THE INERT SOLIDS IN THE COKING ZONE, REMOVINGPRODUCT VAPORS FROM THE COKING ZONE, CIRCULATING THE INERT SOLIDSTHROUGH AN EXTERNAL HEATING ZONE TO RAISE THEIR TEMPERATURE ANDRECYCLING THE HEATED SOLIDS TO THE COKING ZONE TO SUPPLY HEAT THERETO,THE IMPROVED METHOD OF PREPARING A CARBON BLACK FEED STOCK WHICHCOMPRISES THE STEPS OF CONTINUOUSLY FRACTIONATING THE PRODUCT VAPORS TOSEPARATE A HEAVY GAS OIL FRACTION BOILING IN THE RANGE OF ABOUT 700* TO1000*F. AND A HEAVIER FRACTION BOILING ABOVE ABOUT 1000*F., WITHDRAWINGTHE HEAVIER FRACTION, CONTINUOUSLY RECYCLING A PORTION OF THE 700*F. TO1000*F. HEAVY GAS OIL FRACTION TO SAID COKING FOR FURTHER CRACKING ,WITHDRAWING THE REST OF THE 700* TO 1000*F. HEAVY GAS OIL THUS PRO-